Compost, manure + mulch

(Question)

We own a farm, near Nobleton, Ontario. We have access to large quantities of materials to make our own compost. We use fruit and vegetable and plants materials only (never egg shell, or meat scraps), as well as yard waste,  including cedar tree trimmings. We cut and clean our compost to a very small grade, and process it regularly to ensure that no weed seeds will grow. This spring, for some reason, unlike many years in the past, many of my annual seed varieties, both saved from prior year’s seed, and new, did not germinate, including parsley, lobelia and lettuce. I ensured correct light sources, used a heating pad, and the required water. So I’m concerned that I perhaps made my compost too sterile ? One more question: this year I spread mulch under my raspberries and black currents, which made the ground easier to walk on during our spring rainy season. But then the leaves on the berry bushes became yellow, and the yield was low. Also, since I have access to a neighbour’s goat manure, when would be the best time to spread manure ?

 

(Answer)

How wonderful that you’re able to reach out to a variety of materials to create compost for amending the soil for your gardens, and crops! A first consideration: when planting from seed, it’s important to know you have good quality seed to germinate. Yet, considering your experience with planting from seed, and that a wide variety of your seeds did not germinate at all, you are possibly correct that your compost may have been the issue. Ideally, seeds should be grown in a mix that contains, in addition to compost: sterilized soil, coarse sand, peat moss, and vermiculite/perlite. Leaf mould should not be used as it can actually be toxic to seeds, and inhibit germination. The mix should be well aerated, well drained and weed and disease free. Fertilizer is not required until true leaves are produced. at which point a slow-release fertilizer – 14:14:14 – may be added to the growing medium.  Further, regarding your neighbour’s goat manure: you may consider adding it, in part, to your valuable vegetative compost, to create a more fertile balance for this fall, or next season. Manure should be spread as early in the spring as possible, or even in late fall.

And this relates also to your question regarding mulch around your berry bushes, with yellow leaves and low yield.  As you know from your gardening experience,  composting is a natural process that breaks down organic matter for use by the plant’s roots, primarily by the inherent microorganisms. Secondly, the carbon vs. nitrogen ratio of any composted material is very important. Carbons are more complex in structure, and don”t break down easily. Carbon is an  important fuel, and nitrogen is required  for protein-building. But we need to be careful: certain vegetative products are higher in carbon, and should be very well composted before adding to the soil around plants.  For example straw, or pine needles, or cedar branches  (as you mentioned),  are much higher in carbon than vegetable waste. If prior composting hasn’t taken place, then the risk is that microorganisms will first take nitrogen from the soil to break down the excess carbon in the uncomposted organic matter. Hence, in spite of your very good intentions, the berry plants that you had hoped to “feed”, would in fact be starved for nitrogen.  But, (there is always hope)  if a liquid nitrogen fertilizer had been applied at the same time as the uncomposted mulching, a certain amount of the nitrogen deficit to your plant roots could have been mitigated.

You may want to read more specific advice on the composition of compost and manures. The Toronto Master Gardeners, in partnership with the City of Toronto, have prepared a number of Garden Guides on organic fertilizing and soil improvement. All the best in finding the right balance of compost, manure and mulch for your plants !

Here are links to the guides guides:

Improving Your Soil Organically

Compost for Your Organic Garden

Organic Fertilizers

And here is some information about using wood shavings as mulch.